TGSL Tuning & troubleshooting

[BKY1337]

I had about 11-12Volts before when it still worked. My Multimeter is a Mastech , cheap and good.
The oscillator simulator said the same. But i dont have this voltage now.

I will test the components tomorrow.

[dbanner]

I measured 4.1 volts AC on my TX coil with cheap DMM. I know this is wrong. Pull up anode leg of D6, then check for -5V on this leg of D6. If you get -5V, then you have shorted component on board, if you don't get -5V, then you have to check 4024, TR7, TR8, D6, D7. I refer to this schematic when naming components.

[dbanner]

AH HA! There is your problem. You do not have -5Volts. look at tr7, tr8 , d6 and d7. That's your problem right there. Now as for TX voltage, it's supposed to be around 16 volt PEAK TO PEAK. Not -16 volts! I am going to measure voltage on my tgsl coil with cheapo meter and see what I get.

[BKY1337]

Listen carefully, the constant tone in your speaker has nothing to do with your TX oscillator circuit. Your oscillator IS WORKING. MAKE SURE YOU HAVE -5V supply on circuit board. Measure this on pin 4 of any of the chips relative to ground(battery minus). This will tell you power supply is good, from this you can infer that your 4024 is good. Once you have good -5V supply(and +8V which I know you have), then you must look elswhere for cause of constant tone. Don't worry about the voltage amplitude at your TX coil right now, This will not cause constant tone in speaker.

I have +0.73 Volts DC at the Pin 4 . Then i think i should check the negative Voltage supply. I will do this tomorrow, it's late here in Germany.

[BKY1337]

I already wrote this. The coil works but only with a few millivolts.
I know that the coil is ok, because i have used it before.

I played with an online colpitts oscillator and i saw that the voltage there is 9.78V V not -16Volts.



Whats wrong?

[dbanner]

Listen carefully, the constant tone in your speaker has nothing to do with your TX oscillator circuit. Your oscillator IS WORKING. MAKE SURE YOU HAVE -5V supply on circuit board. Measure this on pin 4 of any of the chips relative to ground(battery minus). This will tell you power supply is good, from this you can infer that your 4024 is good. Once you have good -5V supply(and +8V which I know you have), then you must look elswhere for cause of constant tone. Don't worry about the voltage amplitude at your TX coil right now, This will not cause constant tone in speaker.

[homefire]

If your DMM does Freq use it to insure your coil is even working.

[BKY1337]

I use 8x 1,5V Batteries. I have 8Volts where the colpitts is. And i already have replaced the last 358 with a TL082.

I think i should have -16 volts even with a damged LM358. or not?

Do you mean the three diodes at the 4024?

[dbanner]

Your oscillator is working. Yes, you are right about 4024. It is working too. I assume you have approximately -5V supply? Then I think maybe last 358 chip has gone bonkers. Try putting the other 358 chip in its place and see if constant tone disappears. Or check the three diodes.

[BKY1337]

Also the removing of the ics makes no change.

I think i have the steady sound because i dont have -16Volts but im not sure. The signal which comes from the 4024 to the audio section causes the sound. But im not sure. When i remove it, the detector becomes quiet.

[BKY1337]

I tried both , DC and AC. I also checked the 2n2222a (T6). My Transistor tester said OK, NPN.
I measured 4 Volts DC at the collector of T6.

I get 900mv when i use DC at the tx connector to GND Battery. And only a few mV with AC.

I can measure about 14,5 khZ with the black probe at GND and without the red one.

I think i should get -16 Volts when the colpitts is working properly with 14,5 kHz.

[dbanner]

From what you have previously stated(14Khz), seem like your oscillator is working. what setting on meter are you using to measure voltage?

[dbanner]

My TGSL is not surface mount. It is the Kit from Silverdog.
I will try what you said.

Do you mean this ICs ?:

[ATTACH]42017[/ATTACH]

Yes, remove those, this isolates oscillator.

[dbanner]

Also you measured 0.2 volts on pin 8 of LM308. PIN 7 of LM308 is rail voltage(+8V) not pin 8.

[BKY1337]

My TGSL is not surface mount. It is the Kit from Silverdog.
I will try what you said.

Do you mean this ICs ?: